Oxide flotation



Patented Jan. 28, 1936 UNITED STATES a y I 2,029,156

OXIDE FLOTATION Ludwig Christmann, Jersey City, Stuart A. Falconer, Elizabeth, N. J. assignors to Ameri-- can Cyanamid Company, New York, N. Y., a

corporation of Maine I No Drawing. Application November 1, 1928,

I Serial N0. 316,610

4 Claims.

As far as the present discovery is concerned, however, such sulfides are present incidentally.

The recovery of sulfide minerals by the flotation process is now highly developed and reagents adapted thereto are well known in the art. Heretofore, however, the flotation concentration of no oxide ores has been very unsatisfactory. Practically all of the proposed'methods have involved a preliminary sulfidization of the oxide component in an attempt to produce upon the surface of the mineral a coating of sulfide which would :5 render it susceptible to ordinary sulfide flotation very troublesome in practice, partly because some of the oxide minerals sulfidize with difliculty, if at all, and partly because the sulfidizing reagent frequently introduces complications and difficulties in the operation of the flotation cell.

' The essence of the invention is that such oxide minerals are recoveredwithout preliminary sulfidization by employing'a reagent or combination such oxide minerals.

Although certain of the reagents specified in this application are well knownin the recovery of sulfides, it does not follow that sulfide reagents are applicable to oxide flotation, and, as a matter of fact, there is no theory of reasoning by which one could conclude that a sulfide flotation reagent would operate efflciently with oxides. The entire history of the flotation art has shown ,1 that the reverse is true. According to prior practice, values present in non-sulfide form were reagents. This sulfidization operation has proven 3 of reagents adapted specifically to the flotation of moters whose fimction is to collect into aggregates the mineral to be floated, and probably to attach such aggregates to the bubble; second, frothing agents whose purpose is to supply the bubble which is essential for the raising of the heavy mineral particles from'the ore pulp; and third, reagents known as conditioning reagents whose exact function is obscure but which probably serve a variety of purposes such as freeing the solution from soluble heavy metal salts which, if not so removed, would themselves consume the more expensive collectors, and possibly also to establish a proper hydrogen-ion concentration.

The use of such collectors as potassium ethyl xanthate, thiocarbanilid and the dithiophosphates is old in the flotation of sulfide minerals. As has been stated above and as is shown in the results which follow, such collecting reagents are not themselves well adapted to the flotation of oxide minerals except when used in conjunction with certain other reagents as disclosed herein.

As frothing agents, such materials as pine oil and cresylic acid are usually employed. Frequentlythe collector itself has frothing properties, in which case it may be unnecessary to add any specific frothing agent. This is particularly true where oxidized ores are under consideration, since these almost always froth more readily than sulfides. In many of the examples given in this specification, no auxiliary frothing agent has been used, the frothing properties being derived from the collector. In some cases, however, the use of small amounts of frothlng agent may be found advantageous. t

The use of acids and alkalies as modifying, agents is old in the flotation art. As has been shown above, their function is to regulate the hydrogen-ion concentration and frequently to precipitate soluble salts from solutioir. As preferred modifying agents there may be used acids 0 whose heavy metal salts are insoluble, and oxalic, sulfuric and particularly phosphoric acid have been found to be eiiective. The only'explanation of the action of these modifying agents is that their function is to convert the metal or metals 4,5 to be recovered into a form which makes them more readily collected by the reagent combinations which are employed. a

One of the important features of this discovery is that oxides are particularly amenable to fiotation in the presence of a mercaptothiazole or derivatives thereof, either with or without frothing agents. It has also been found that good results are obtained in oxide flotation by combining a mercaptothiazole or its derivative with other to well or lesser known flotation reagents, the result being considerably more efficient than either reagent used alone.

Among the reagents which have been found efiicient are: the mercaptothiazoles, mercaptobenzothiazoles and particularly the sodium salt thereof, 4 methyl and 6 chlormercaptobenzothiazole, dithiophosphoric acids, the disubstituted dithiophosphoric acids and particularly the sodium salt of diisopropyldithiophosphoric acid, as well as the ammonium and aniline salts thereof, mixtures of soda ash and a disubstituted dithiophosphoric acid, the alkyl xanthates, particularly amyl xanthate, and the potassium salts thereof and mixtures of cresylic acid and the disubstituted dithiophosphoric acids such as the diaryldithiophosphoric acids.

Tests have shown the efficacy of these reagents and combinations thereof in the recovery of copper, lead, silver and gold.

In Table No. 1 the ore was from one of the properties of the International smelting Company in Utah and known as the North Lily mine, which analyzed as follows:

Percent Total lead 29.60 Non-sulfide lead 25.93 Total zinc 0.53 Non-sulfide zinc 0.45 Iron i 6.96 Sulfur 4.90 Insoluble 42.35

CaO 1.33 MgO 0.28 Cu 0.065

Au, oz./ton 0.155 Ag, oz./ton 11.93

The flotation results on copper, listed in Table The Bagdad Copper Company which analyzed as follows: i

Per cent Total copper 3.27 Non-sulfide copper 3.07 Iron. 2.52 Insoluble 82.4

Unless otherwise noted the procedure was substantially as follows: I

Approximately 1200 grams of ore were ground with 1200 grams of water with orwithouta reagent in a rod mill for 10 minutes. The pulp was then transferred to a laboratory, mechanically agitated, flotation cell and diluted to 22% solids. This pulp was then subjected to a flotation operation for thetime indicated.

ing properties to the pulp, or else sufficient frother No. 2 were had from tests made upon ore from was added.

Table N 0. 1

Weight Concentrates To rod mill Reagent in lbs. per ton gif Pei cgnt g Au Ma st Cone. Tails Pounds Re- (min.

(gm) (gm) Grade I 7 L per ton agent Start 5 min. 10 mm. 15 min.

Recov, Reeov. Recov.

62. 9 29.53 0.42 1.0 NaMLBT 0.5 N a-MBT 3 457 711 5 HsPOl 15 0 1 4 1.0 Aero-X 0.5 Aero-X 57. 8 26. 44 0. 245 1.0 NaMBT 0.5 NaMBT 0.5 NaMBT 4 520 646 1 H3P0 1.0 Aero-X 0.5 Aero-X 0.5 Aero-X 2o 61. 2 28.85 0. 25 5 430 735 3 HaPO4 do do fi 20 57. 4 25. 65 0. 255 6 527 647 5 H3POA dodo 20 62. 9 29. 54 0.26 1.0 NaMB'I 1.0 NaMBT 7 470 705 5 H3PO4 0.5 NH4 0.5 NH4 15 88.0 87.8 65.9 DIPDTP DIPDTP 66.6 1.0 NaMBT 1.0 NaMBT 8 424 727 5 H3PO4 0.5 NaDIP- 0.5 NBDIP- 15 85. 2 DTP DTP 1.0 NaMBT 0.5 NaMBT 0.5 NaMBT 9 898 5 6 H 1.0 Aero-X 0.5 Aero-X 0.5 Aero-X 58. 3 10 426 753 3 H1804 do d0 do 20 56. 7 26. 98 0. 26 11 532 633 1 H280 d0 d0 do 20 49. 8 23. 48 0. 22 12 603 566 (10-... do d0 20 all) Table 150. 1-0ontimted Weight Concentrates To rod inill Reagent in lbs. per ton TV T i is l 1 Y i Cone. Tails g 11 Pounds M e min.

(gum) (gum) Grade L per ton 1 agent Start min. 1 2 10111111. 15 mm.

Recov. Recov Recova V 5s. 35 2s. 02 0.19 T 4a 460 712 5 0 mp0. k gfigf 1.0 CMBT 1.0 OMBT 1.0 CMBI 2o 64.10 26. 6 0.20 i a 480 702 5 5.0 HIPOA gt tgi 1.0 MMBT 1.0 MMBT 1.9 MMB'I 2o v Table No. 2 Weight Cone. Tails To rod Reagent'in lbs. per'ton Time of Test Percent Cu Percent Cu fl Grade Grade g Reagent Start 5 min.

7 Becov. Reeov.

i i 24. 19 a 12 127 95 1073 1 SBFO 1.0 NaMBT 15 J i 50.2- 49.8 g W g 17. 81 1. 3e g 1.0 NaMBT 128 168 1005 65 8 3L 2 2 SBFO TAROL 15 1a. 51 1. 4t! 230 951 4 SBFO 2.0 NaMBT 15 69.8 30. a; n

Tests 6, 12, 17, 19, 27 and 28 show the efliect on oxide recovery of the mercaptothiazoles: in natural and phosphoric acid circuits, together with the efiect of Aero-X in nature; and phosphoric acid circuits, and both reagents in combination. A comparison of these tests shows the remarkable efiect of NalVlZB'I" on oxide ore in the presence of Aero-X. It also appears that phos- 4 phoric acid increases the oxide grade appreciably.

Tests 9, 10, 11 and 12 were made to determine the efiect of sulfuric acid on 'oxide grade and recovery in a circuit ineluding NaMBT and Aero-X.

These tests show that a. small amount of sulfuric acid increases the grade of concentrate without increasing recovery appreciably, and that large amounts of sulfuric acid do not further increase the grade but on the otherhand, do materially efiect recovery.

Tests 12, 13, 14 and 15 demonstrate the eflect of oxalic acid as a typical organic acid on oxide grade and recovery, using the same reagents as above. These'tests show that a small amount of oxalic acid increases the grade without increasing recovery and that larger amounts of this acid cause a. falling off of recovery without, however, affecting the grade.

Tests4, 5, 6 and 12 were made in much the same manner using phosphoric acid as the re- 60 agent in the rod mill. These tests show that phosphoric acid materially increasesthe grade and gives some increase inrecovery. The plans-- phoric acid added even in equivalents of as much as 5 pounds per ton do not cause a decrease in 65 recovery, so that phosphoric acid is to be preferred as compared with sulfuric or oxalic acids.

A comparison of tests 8, 19. 21, 27 and 32 shows the effect of NaDIPDTP, alone, NaMBT both alone and together using AF15 as a frother.

7 These tests clearly show thatthe combination of NaMBT and NaDIP-DTP is better than either alone and rema'rkabie results are had from this combination.

Tests 16, 17. and 28 show the effect of one of '7 the disubstituted dithiophosphoric acids, and

particularly the aniline salt of the diisopropyl form with sufficient frothfer, in both natural and acid circuits, on lead recovery. They show that with Aero-X a natural circuit gives somewhat poorer grade but slightly better recovery, and that even large amounts of Aero-X do not appreciably increase recovery.

Tests 20, 21 and 32 demonstrate the eifect of the disubstituted;dithiophosphoric acids, using AF15 in both natural and acid circuits. These tests seem to indicate that with sodium diisopropyldithiophosphoric acid, free phosphoric acid increases both grade and recovery. Large amounts of the fiotation'reagentfin acid circuit give an appreciable recovery.

Tests 6, 7, 8 and 22 were made to study the effect of the mercaptothiazoles in combination with various members of the disubstituted dithiophosphoric derivatives in phosphoric acid circuits. These tests clearly show that good flotation combinations may be had with these reagents.

Tests 19, 24, 27, 30 and 31 demonstrate the effect on oxide recovery of KAX and NaMBT alone using AF15,,and in combination, in natural and phosphoric acid circuits. From these tests it would conclusively appear that the combination of NaMBT and KAX is better than either alone.

Tests 41 and 42 show the beneficial effects of other mercaptobenzothiezoles in combination with KAX.

A run was made following the procedure of test 24, using only one pound H3PO4 per ton in the rod mill, the grind being carried out to the following point:

This test recovered 96% Pb of a 58.04% grade, 93.3% Ag of a grade of 25.83 oz. per ton, and

76.0% Au of a grade of 0.21 oz. per ton. These results show increased recovery may be had by grinding as above, although there is a. slight decrease in grade.

A-lesser grind in which 74.30% passeda 200 mesh screen recovered 95.9% Pb of a 60.18% grade.

Following the procedure of test 6, but grinding in the rod mill until 74.75% passed a 200 mesh screen, 95.2% Pb was recovered in a froth of a 51.31% grade. This confirms the deduction as to the efiect of grinding, as made in connection with the test compared with test 24.

A comparison of tests 24, 25 and 26 shows the efiect of the mercaptothiazoles in.combination with various members of the alkyl xanthate series in phosphoric acid on oxide recovery. These tests appear to indicate that the potency of the various xanthates with sodium mercaptobenzothiazole are in the following order: KAXKEX The effect of various reagents plus sodium mercaptobenzothiazole in phosphoric acid circuits is shown in tests 34, 35 and 36.

Tests 43 and 44 show excellent recovery with various thiazoles using tarol as a frother.

A comparison of tests 21, 31 and 33 seems to indicate that sodium diisopropyldithiophosphoric acid with AF15 as a frother is a better reagent than the combination KAX, and N aDIPDTP.

The effect of the alkyl xanthates above in natural circuit and using AF15 in phosphoric acid circuits, on oxide recovery, is shown in tests 30 and 31. There it is found that in an acid circuit with AF15, grade is increased slightly and recovery decreased. In either natural or acid circuit recovery may be had by KAX alone.

A comparison of tests 3, 4, 5, 6, 7, 11,12, 13,

allel, and exceptionally good results as to total recovery may also be had by the use of these reagents.

. From a comparison of tests 27, 28 and 29 it will be seen that as much as 69% of the copper can be recovered in a grade averaging 18%, with sodium mercaptobenzothiazole, Scotch blast furnace oil and tarol.

It is to be clearly. understood that the results here tabulated are merely indicative as to the types of reagents and reagent combinations which will float oxide ores. Obviously the amounts of reagents specified are not considered absolutely necessary, and it is distinctly under- Stood that this discovery is not limited to the proportions indicated. The discovery lies principally in the fact that certain reagents may be used with exceptional advantage in flotation processes for the recovery of the heavy metals from oxide ores.

We claim:

1. A method of concentrating oxidized ores which includes the step of subjecting an oxidized ore to a froth flotation operation in the presence of a mercaptobenzothiazole, a diisopropyldithiophosphoric acid salt and phosphoric acid.

2. A method of concentrating oxidized ores which includes the step of subjecting an oxidized ore to a froth flotation operation in the presence of sodium mercaptobenzothiazole, sodium diisopropyldithiophosphate and phosphoric acid.

3. A method of concentrating oxidized ores which includes the step of subjecting an oxidized ore to a froth flotation operation in the presence of sodium mercaptobenzothiazole, phosphoric acid and a frother.

4. A method of concentrating oxidized ores which includes the step of subjecting an oxidized ore to a froth flotation operation in the presence of a mercaptobenzothiazole, a frother and phosphoric acid.

LUDWIG J. CI-IRISTMANN. STUART A. FALCONER. 

